Human Biology BIOL-120 Lecture 13 The Reproductive Systems
Excretory System
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I. The urinary system functions to control water & minerals and remove wastes (urea mainly) from the blood II. The kidneys are the major organ of excretory system A. Ureters lead from kidney to bladder B. Urethra leads from bladder to outside of body a. Exist internal and external urethral sphincters C. In females, urinary and reproductive systems separate with urethra passing to surface between the clitoris and the vaginal opening in the vulva D. In males, both urine and semen pass out the urethra from the penis a. During sexual arousal, internal sphincter closes to prevent urine from flowing into urethra during sexual intercourse III. The excretory and genital organs are collectively called the urogenital system
CHAPTER 16 16.1 Male reproductive system I.Since chance of one sperm fertilizing an egg is very slim, strategy is to deliver large number of sperm at one time II.Exist several reproductive organs although only the penis and scrotum are visible III.Testes is site where sperm made A.Differentiate from tissue that become abdominal wall B.Just before birth, testes drop into outpouching of skin & smooth muscle called the scrotum 1.Allows sperm to develop at a temperature a few degrees lower than body temperature – will regulate C.2 inches long but have 100 yards of seminiferous tubules (where sperm form) D.The many seminiferous tubules join into the epididymus 1.Epididymus located just outside the testis IV.Epididymus joins into long vas deferens (ductus deferens) V.Sperm development A.Not motile when leave seminiferous tubules B.Continue to mature in epididymus & vas deferens where sperm stored until ejaculation VI.Vas deferens from each testicle join the short ejaculatory duct VII.When sexual climax reached in male, the sperm move from the epididymus & vas deferens into the ejaculatory duct from where they are propelled into the urethra and out of the penis – urethra carries both urine and sperm VIII.Penis is the male organ of sexual intercourse – purpose is to deliver sperm internally in the female A.Erectile tissue which allows penis to increase in size and stiffness B.Caused by vasodilation and flow of blood into tissue – same event that occurs in the female’s labia and clitoris IX.Sperm delivered in semen A.Secretions of seminal vesicle, prostate, and bulbourethral glands B.Seminal vesicle produces seminal fluid – 60% of semen & has fructose and prostaglandins (nourishment and biological active molecule) C.Prostate produces a alkaline fluid that neutralizes the environment of the vagina which is normally acidic (defense mechanism) D.Bulbourethral gland secrets mucous into urethra during sexual arousal to clear acidic urine and for lubrication during intercourse X.Sperm produced by meiosis in seminiferous tubules A.Takes 9-10 weeks to occur, 10s of millions produced each day 1.100-300 million sperm will be delivered during intercourse 2.If egg fertilized, only one sperm will be involved B.Sertoli cells are support cells that nourish the developing sperm
Human Biology BIOL-120 Lecture 13 The Reproductive Systems
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1.Make up bulk of seminiferous tubules C.Leydig cells make testosterone 1.Located between seminiferous tubules aTestosterone determines the rate at which sperm form bControlled by pituitary if gets too low or too high cLH & FSH released by pituitary (1)LH stimulate testosterone production (2)FSH stimulates Sertoli cells for their function D.Sertoli cells make inhibin if too many sperm being produced – lowers FSH secretion by pituitary 16.2 Female reproductive system produces eggs and supports pregnancy I.Evolved to perform more functions than the male A.Cycle for release of egg and preparation of uterus for fertilized egg B.Support developing baby C.Feed baby after birth II.Ovaries are primary reproductive organs A.Develop from same tissue as testis in developing fetus (destined for abdominal wall) B.Secrete estrogen & progesterone III.Egg picked up by oviduct which has fimbriae to help direct egg into opening A.Egg usually fertilized in upper 1/3 of oviduct IV.Takes 3-4 days for egg to makes its way down oviduct into the uterus A.If egg fertilized, will implant in endometrium of uterus B.Will help form the placenta to nourish developing fetus C.Myometrium is thick layer of smooth muscle, is outer layer of uterus 1.Stretches with increasing size of fetus 2.Contracts during birth to push baby out of uterus into birth canal D.Narrow lower part of uterus is the cervix 1.Narrow opening that allow sperm in and baby out V.Cervix joins the vagina – organ of sexual intercourse and birth canal A.Hollow muscular organ B.Exist glands within the vagina that produce lubricating secretions during sexual arousal C.Hymen is thin ring of tissue that partially covers the vagina and is usually ruptured during the first sexual intercourse, tampon insertion, or vigorous physical exercise VI.Vagina is continuous with external genitalia, collectively called the vulva A.Includes labia majora and labia minora B.Clitoris – partially enclosed by labia minora; originates from same tissue as penis during early development 1.Like penis, has erectile tissue and highly sensitive to stimulation 2.Between clitoris and vaginal opening is the urethral opening VII.Mammary glands are present in the breasts – support infant’s development A.Develop during puberty - estrogen B.Preparation for lactation – estrogen & progesterone C.Nipple, areola, milk ducts, lobules, fat, muscle D.Start of lactation at birth under endocrine control – prolactin E.Delivery of milk to nipple during nursing also under endocrine control – oxytocin 16.3 Menstrual cycle consists of ovarian and uterine cycles I.Approx a 28 day cycle that releases egg and prepares the uterus for implantation of fertilized egg A.Under hormonal control II.Have all the eggs in ovary at birth and is not a continual production like sperm in male A.Stopped in the middle of meiosis III.Starting at puberty, each month about a dozen primary oocytes start maturing but only one will complete it – only 400 to 500 eggs will be released during a women’s lifetime
Human Biology BIOL-120 Lecture 13 The Reproductive Systems
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IV.Ovarian cycle A.Follicle ovulation corpus luteum B.Chorion membrane of developing embryo secrets chorionic gonadotropin (hCG) 1.Pregnancy tests look for hCG 2.Maintains corpus luteum for 10-12 weeks by which time placenta can make enough progesterone & estrogen to maintain pregnancy aPrevents ovulation from occurring during pregnancy V.Uterine cycle A.Summary - Menstrual phase (days 1-5) proliferative phase (6-14) ovulation (14) secretory phase (15-28) B.Menstrual phase – breakdown of endometrium of uterus and rupture of blood vessels causes menstrual flow (triggered by tail off of estrogen & progesterone) C.Proliferative phase – endometrium grows in thickness and cervical mucous appears (increase in estrogen) D.Ovulation – egg released into oviduct (from rising estrogen get an LH surge which triggers) E.Secretory phase – endometrium continues to thicken (3X thickness after menstruation, glycogen granules form, mucous plug forms in cervix (progesterone & estrogen of corpus luteum) 16.4 Human response, intercourse, and fertilization I.Human sexual response can have up to 4 phases to accomplish sexual intercourse and fertilization A.Excitement – increase sexual excitement & arousal B.Plateau – intense & continuing arousal C.Orgasm – peak of sexual excitement D.Resolution – arousal subsides II.Male sexual response A.Excitement is associated with pleasurable sensation in penis and erection of penis 1.Stimuli through all the senses contribute – touch, smell, sounds, sight, taste B.Breathing & heart rate quicken C.Tone of skeletal muscles increase D.Arousal continues through plateau stage which can last from seconds to several minutes E.Arousal peaks with orgasm 1.Intensely pleasurable reflex that results in expulsion of sperm from penis – ejaculation 2.Sympathetic nerve activity cause contraction of smooth muscle in epididymus, seminal vesicles, prostate, and bulbourethral glands to send semen into urethra 3.Internal urethral sphincter closes behind semen to prevent urine from mixing with secretion 4.Skeletal muscles at base of penis contract rhythmically forcing semen out of urethra in several spurts (approx teaspoon volume typically) F.Resolution phase sees erection subside and heart rate & breathing return to normal rates 1.Usually refractory period follows when another erection & orgasm not possible a. Can last several minutes up to several hours III.Female sexual response A.Same 4 stages experienced B.Excitement is associated with pleasurable sensations especially in clitoris and breasts a. All senses come into play C.With increased arousal comes dilation of blood vessels of clitoris, labia, & nipples of breasts D.Vagina and area around labia secrete mucous lubrication for sexual intercourse E.Female orgasm consists of rhythmic, involuntary muscular contractions of vagina and uterus 1.Intense feelings of pleasure, warmth, and relaxation
Human Biology BIOL-120 Lecture 13 The Reproductive Systems
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2.The rate and frequency of orgasm in a sexual experience is more variable in females compared to males F.Female arousal and orgasm not required for fertilization of egg & pregnancy IV.Fertilization A.Occurs during coitus when sperm deposited by male in vagina near cervix - result of pelvic thrusts by male which stimulate penis to orgasm & ejaculation B.Sperm make their way through cervix and through the uterus and up the oviducts C.Journey can take hours or days until one sperm fertilizes the egg of the female D.Some sperm can be viable for 5 days but most live only 2 days 16.5 Birth Control Methods I.Sterilization A.Vasectomy (vas deferens) B.Tubal ligation (oviducts) II.Hormonal methods A.Pills B.Patches C.Implants D.Injections III.Intrauterine devices IV.Diaphragms & cervical caps V.Chemical spermicides VI.Condoms 16.6 Infertility: Inability to conceive I.In males can be caused by low sperm count A.Artificial insemination may be way to go II.In females can be many reasons A.Infections in females B.Abnormal FSH & LH C.Abnormal secretions – too acid or viscous D.Endometriosis – cervical tissue has migrated to ovary, bladder, colon E.Age related III.Options A.Artificial insemination B.In vitro fertilization C.Fertility enhancing drugs D.Surrogate mothers E.Adoption 16.7 Sexually transmitted diseases: A worldwide concern I.12 million people contract a STD each year – ¼ are teenagers II.Gonorrhea A.Caused by a bacterium – Neisseria gonorrhoeae B.Passed by genital contact or genital/oral contact C.Mother can pass to baby at birth – blindness D.Painful urination and discharge from penis & vagina E.Usually respond to antibiotics 1.Some antibiotic-resistant strains III.Syphilis A.Caused by bacterium – Treponema pallidum B.One of most dangerous if left untreated C.Occurs in 3 phases – third phase is wide spread cardiovascular and nervous system damage, blindness, death D.Penicillin can treat
Human Biology BIOL-120 Lecture 13 The Reproductive Systems
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IV.Chlamydia A.Caused by bacterium – Chlamydia trachomatis B.Most prevalent of all STDs C.In males – burning sensation during urination, discharge from penis D.In females – vaginal discharge, burning / itching sensation E.Can cause pelvic inflammation which could lead to sterility F.Newborn could suffer eye and lung problems – pneumonia V.Viral STDs A.HIV B.Hepatitis B 1.Transmitted in blood / body fluids 2.More contagious than HIV C.Genital herpes 1.15% of population 2.Genital blisters, painful urination, fever 3.Disease comes and goes but never leaves 4.No cure known but drugs to control active infectious stages when blisters develop 5.Dangerous for infant – blindness D.Human Papiloma virus (HPV) 1.Warts in genital areas and anus; recur 2.Related to cancers of penis and cervix 3.75% women will be infected 4.PAP and vaccine available VI.Others A.Yeast infections – Candida B.Lice – “crabs”
